24 October 2012

Dino DNA: is there or isn’t there?

This press release is showing up in my social media feeds because it claims that researchers have got dinosaur DNA.

Schweitzer and her team also tested for the presence of DNA within the cellular structures, using an antibody that only binds to the "backbone" of DNA. The antibody reacted to small amounts of material within the "cells" of both the T. rex and the B. canadensis. To rule out the presence of microbes, they used an antibody that binds histone proteins, which bind tightly to the DNA of everything except microbes, and got another positive result. They then ran two other histochemical stains which fluoresce when they attach to DNA molecules. Those tests were also positive. These data strongly suggest that the DNA is original, but without sequence data, it is impossible to confirm that the DNA is dinosaurian.

Expression of doubt.

We went down this road before in the 1990s. There were multiple papers that was claiming to have found DNA that was tens of millions of years old, with at least one claiming to have closed in on the 65 million year point that was the end of the dinosaur era. Those claims could not be replicated, and are now widely viewed as flase alarms coming from contamination.

Another paper by Allentoft and colleagues just weeks ago argued that DNA’s half life was too short for us to be likely to get any usable DNA from 65 million years or older. See this Wired article with the great title, Jurassic Park impossible because of stupid laws of physics, for a summary.

So the claim of DNA in this new research? I'll bet a dollar it's either degraded beyond any usefulness, or that it’s an some sort of artifact. Antibodies are tricky things.

I’m much less skeptical about the claims the team found ancient proteins. Proteins come in all sorts of varieties, and some are no doubt more stronger and more stable than others.

Maybe I’m just skeptical because my heart’s been broken too many times by this line of research... “We’ve got something...! Oh, wait... no we don’t. We’ve got... ooops. Looking good... er...”